Influence of substructures on the selective laser melted Ti-6Al-4V alloy as a function of laser re-melting

Abstract

This study investigates the effects of melting sequence on the microstructure, substructure, and mechanical properties of SLM Ti6Al4V alloys. Acicular α′ martensite was observed in all the SLM samples, and the dimensions of the α′ phase were changed with the melting sequence. Twins appear between acicular α′ martensite, and a large number of dislocations were observed in the material and within α′ martensite. The density of twins and dislocations increased with increasing melting sequence from single melting to triple melting. Tensile strength properties including ultimate tensile strength and yield stress, and hardness increased with increasing melting sequence from single melting to triple melting. The present results clearly prove that the melting sequence plays a significant role in determining the microstructure, substructure, and mechanical properties of the SLM as-built materials. • The as-built SLM shows high density of twins and dislocation. • The density of twins and dislocation increased with re-melting. • Ultimate tensile strength and yield stress increased with re-melting. • Re-melting–microstructure–substructure–mechanical property relationships are investigated.